CZ20002413A3 - Method for regulating a generator with regard to optimum output and efficiency thereof and apparatus for making the same - Google Patents

Abstract

A method of controlling a diode-assigned generator (G) the bridge of the converter, in particular the synchronous machine, in which it is excitation current (IE) flowing through the field winding (LJ controls) so that the generator output voltage reaches a predetermined and, in addition, the generator phase currents are controlled, se carried out by creating at least three regulatory areas in which excitation current regulation is performed according to various criteria (IE) and generator phase currents. Regulatory Discovery in particular, depending on the frequency of rotation a performance. The regulation expands on excitation current (IE), as well as phase current, and is performed with various controllers that exchange information with each other. The device includes an excitation current controller (ER) (IE) generator stator current regulator (SR) (G) superior controller (OR) and voltage regulator (SpR).

Description

A method of control, optimized in terms of power and efficiency, of a generator and a device for carrying out the method

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a power and efficiency optimized control method for an inverter-connected generator, in particular a synchronous machine, in which the excitation current flowing through the excitation winding is controlled so that the generator output voltage reaches a predetermined height. The invention further relates to a power-optimized control device, a generator, in particular a synchronous machine.

BACKGROUND OF THE INVENTION

In a motor vehicle, claw-pole generators are currently mainly used for power generation. Clawed-pole generators are three-phase current generating machines which can be described approximately on the principle of a synchronous high-pole machine. Typically, the three-phase output current of the generator is rectified by a passive diode bridge B6, and such an arrangement is shown in FIG. The generator is controlled by the excitation current so that the generator output voltage Ub is set to a desired value independent of the rotational frequency and, to the extent possible, also independent of the load. The power supply by the generator as well as the corresponding rectifier circuit, as shown in FIG. 1, only starts after a certain rotation frequency, the so-called initial rotation frequency, has been reached. At • • * v · * * rotation frequencies that are less than the initial rotation frequency, the generator voltage is less than the battery voltage. In this case, no power can be supplied to the vehicle electrical network via the rectifier bridge B6.

One possibility to increase the output of the clawed pole generator is to increase the excitation current. This increase in excitation current, however, results in significant magnetic saturation phenomena at the conventional dimensions of claw-pole generators used in vehicles. These saturation phenomena can significantly reduce performance gains. In addition, a significant increase in the excitation current during continuous operation leads to a thermal overload of the generator, so that this method can only be used for a limited period of time.

Another possibility to increase the power is to change the number of stator windings. Increasing the number of stator windings leads to a decrease in the initial rotation frequency and an increase in the output power in the low rotation region. In this case, however, the output power is substantially reduced in the range of medium and high rotational frequencies. Reducing the number of stator windings leads to an increase in power in the region of high rotational speeds, but at the same time the power in the region of the lower rotational speeds is reduced and the initial rotational frequency is increased. Therefore, a change in the number of stator windings does not result in a target that represents an increase in power over a wide range of rotational frequencies.

DE-P 197 33 221.8 discloses how, by means of an actuator downstream of the generator, and by varying the number of stator windings, the performance characteristics of the generator can be advantageously changed. If the number of stator windings is reduced as described in patent application DE-P 198 45 569.0 and a diode rectifier is connected downstream of the generator, the power will increase. • 4 ··

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444 4

43 4 · 4 * 4 4

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4 «44 44 44 in the mid- and high-speed range. In the lower frequency range, the generator voltage is increased to the voltage level of the vehicle's electrical system by the controller.

A major disadvantage of rectifying the three-phase generator currents by passive bridge B6 is that the magnitude and phase of the phase current or the angle of the magnet wheel cannot be used as an action variable to control the generator. The phase voltage in this case is fixed by the voltage of the vehicle's mains and the phase angle between the phase current and the phase voltage is φ = 0 at all operating points with a good approximation. Therefore, the machine cannot be optimally guided at all operating points regarding output power. , efficiency and dynamics of regulation.

If the Π generator is operated together with the pulse inverter, this limitation no longer exists. Also known in the art are the use of a claw-pole generator in conjunction with a pulse inverter.

DE-P 197 33 212.9 discloses a method for controlling a generator driven by an internal combustion engine. There is provided the possibility of operating two control ranges, namely the basic rotational frequency range at low rotational frequencies and the magnetic field attenuation range at high rotational frequencies. The method of regulation is not mentioned here. The excitation current control is not mentioned here. However, the uncontrolled actuation of the field current causes the machine or generator to be guided without optimizing performance and efficiency.

U.S. Pat. No. 5,648,705, and optionally EP 0 762 596 A1, discloses a method in which the increase in power in the lower range of rotational frequencies is effected by varying the angle between the phase current and the "

4 * 4 4 · 4444

4 44 44 «· 44 by the magnet wheel voltage. The elaborated concept of regulation is not mentioned here. If Π is not required for the maximum output power in the lower frequency range, the three-phase generator current is set using a passive diode bridge and a single excitation current control to the desired output voltage. For the passive diode bridge, the parasitic diodes of the MOSFET rectifier circuit switch are used. However, regulation in the range of medium and high rotational speeds is not mentioned. Thus, machine guidance, optimum in terms of performance and efficiency, is not achieved at medium and high rotational speeds at full and partial load.

U.S. Pat. No. 5,663,631 discloses a generator control in which the machine drive current Ie is determined by the controller exclusively by the difference ÁUb = Ubsoii - U _B ist between the setpoint U _B soii and the actual value U _B j _{s of the} DC output voltage. The angle 6 of the machine magnet wheel is set to δ = 90 ° for maximum output power. At the same time, reference is made to the possibility of operating the machine by appropriately selecting the angle of the magnet wheel at the optimum efficiency point of operation. It is stated that the precise adjustment of the angle of the magnet wheel can be made depending on the field current. How the angle of the magnet wheel must vary precisely according to the field current is not shown here.

An essential feature of this method is that the determination of the field current is only dependent on the control difference UU _B. The correction of the angle of the magnetic wheel indicated in this patent is only performed in dependence on the excitation current.

In contrast to the known method, it is stated in the method defined in the claims that for each rotational frequency and for each desired power of the generator it can be freely selected

0 00 ··· 0 0 0 0 0 0 0 0 0 0 00 0 «« 0 00 magnitude and phase of field current and phase current. This provides the best possible choice of all possible operating states of the machine or generator, according to the current requirements and to set the most suitable operating point accordingly. In the present invention, the required output power not only affects the desired value of the field current, but directly all machine control parameters that are relevant to the machine guidance.

The method described in U.S. Pat. No. 5,663,631, unlike the present invention, has the additional disadvantage that the control dynamics are determined by an excitation circuit. Therefore, this method has the same disadvantage as regards the rectification by means of the passive diode bridge B6 in terms of behavior under large load changes. Therefore, power changes are dynamically controlled only by large excitation time constants. However, in the present invention, the magnitude and phase position of the phase currents is additionally used for dynamically valuable control of large load jumps.

SUMMARY OF THE INVENTION

The aforementioned drawbacks are eliminated by a power-optimized control system of the generator with an associated bridge of the converter, in particular a synchronous machine, in which the excitation current flowing through the excitation winding is controlled so that the generator output voltage reaches a predetermined height and Generally, at least three control regions are formed in which the drive current and phase currents of the generator are controlled according to various criteria.

The aforementioned drawbacks are further eliminated by the power and efficiency optimized control device of the generator

»· • · ·· • t Φ • * • · · · «« · ·· · ··

with an associated bridge of a transducer, in particular a synchronous machine, with a controller for controlling the excitation current flowing through the excitation winding, and with another controller for regulating the phase currents of the generator according to the invention.

The method and apparatus for regulating the generator have the advantage that both the available output power and the efficiency of the generator are substantially increased over a wide range of rotational frequencies compared to the passive diode rectifier generator.

In addition, in the described manner, a significant improvement in the control dynamics is achieved, for example in the event of a sudden unloading or reduction of the load. Current generators are protected against sudden surge by means of rectifier diodes designed as Z-diodes. If the generator is to produce a higher voltage on the vehicle's electrical network, such as Ub = 42V, there will be considerable problems in producing Z-diodes with higher voltages. To achieve overvoltage protection at sudden unloading and at higher generator voltages, for example at Ub = 42V, other methods must be selected for voltage limitation. The disclosed method advantageously combines increasing the power and efficiency of the generator with effective surge protection in the event of sudden relief.

These advantages are achieved in a manner consisting of a total of four different control regions for generator control. One of the four control regions is selected according to the respective requirements and boundary conditions, for example according to the desired output power and the given rotation speed of the generator. In this way, considerably more advantageous machine guidance is possible over passive rectification operation, which achieves an increase in achievable output power, efficiency and control dynamics.

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The methods according to the invention are advantageously applicable to both synchronous machines and smooth rotors and to synchronous machines with excellent poles, as well as to generators based on similar functional principles, for example clawed pole generators. In this case, the machine windings can be arranged in both a star and a triangle. For example, one method is illustrated on an idealized synchronous machine with high poles. For machines which have similar functional principles or appreciable additional effects, such as a pronounced magnetic non-linear behavior, the described method can be used with similar considerations.

Further advantages of the invention result from the measures set forth in the subclaims,

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated with reference to the accompanying drawings and the following description.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates the essential components of a passive rectifier generator G for understanding the invention. FIG. 1 shows a conventional method of producing direct current by a claw-pole generator and a diode bridge that is currently used in motor vehicles. The field winding has inductance Le and field current Ie. The stator has an inductance Ls, also referred to as phase inductance. The windings have a voltage Up of the magnet wheel and a resistance R. The diode bridge comprises diodes D1 to D6 and is connected to the voltage Ur of the vehicle's electrical network, respectively the battery voltage.

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0 ·· 0

0 0 00 00 00 00

The basic arrangement of the whole system is shown in Fig. 2. The generator G is connected via the elements of the pulse inverter PWR to the DC link capacitor ZK and to the battery BA. The VO detects the rotation speed n of the generator G and the rotor position. Further, the drive current controller ER, the stator or phase current regulator SR, the parent OR regulator and the voltage regulator SPR are shown. Other variables contained in FIG. 2 will be explained in more detail in the following description.

The required power P _so ii of the generator G is determined by a voltage regulator SpR, for example a PI regulator, by regulating the deviation between the desired value and the actual battery voltage Ubsoii - Ubisi- The VO position and frequency detection device detects the rotor position and the generator rotation speed. position detection and rotation frequency may be based, for example, on optical, magnetic or mechanical principles. Furthermore, there are also methods that do not use sensors to determine the position of the rotor and its rotational speed from machine terminal values. These methods are known and therefore need not be described in detail.

The input values for the master controller UR are the required power Ps _O n of the generator G, the frequency nG of the generator G and the voltage Ubisi between the circuits. One of the four control areas is selected by the master controller UR.

As shown in Fig. 2, the output values of the superordinate controller 10 are the setpoint value of the phase current Issoii, the phase position of the phase current jj / goii, the longitudinal component Idson of the phase current and the transverse component Iq ₅ oii of the phase current. Iesoii excitation current. This makes it possible for the required G for each rotation frequency and power of the G generator to be controlled by the voltage regulator, arbitrarily. always select the most suitable operating point.

The input values of the stator current regulator SR are the rotor position and the rotational frequency n.G of the generator G, the required phase current values and the measured currents of the Ilyia and Ilyia in the conductors. From these two measured streams of Ilyia and Ii.ist; In the conductors the phase currents of the generator G can be calculated. Alternatively, all three currents in the conductors or two or three phase currents can also be measured.

The stator current regulator SR controls the six PWR impulse inverter switches (Fig. 5) in an appropriate manner to supply phase current according to size and phase. The PWR pulse inverter switches can be designed, for example, as MOSFETs as shown in FIG. 5. Generally, many possible methods of supplying phase and phase currents to a three-phase machine using a pulse inverter are known, so there is no need to describe them in detail.

The principle curve of the control zones 1-3 in dependence on the generator output Pgen G and the frequency n of the rotation of the generator G is shown in Fig. 3.

In operation with the rotational frequencies to the left of the limit line N23, no power can be drawn in operation with the passive bridge B6, since in this case the output voltage of the generator G is less than the voltage Ub of the vehicle's electrical network. Boundary line N23. corresponds to full load of generator G with passive bridge B6. By means of the control regions 1 and 2, the generator G can produce power even at very low rotational frequencies. Therefore, the initial rotation frequency no, which is important in passive rectification, is no longer relevant in the method of the invention.

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 99 99 99 99 99 99 99 99

FIG. 6 shows how the power characteristic of the generator G changes as the number of stator windings changes. If the number of stator windings is reduced from w1 to w2, the power at high rotational speeds is increased. The boundary lines Nu and move according to the higher rotational frequencies. However, the maximum output power achievable in the very low range of rotation frequencies remains constant and runs in region 1 independently of the number of stator windings on the same straight line.

Regulatory Areas 1-3 also represent areas of varying efficiency. Therefore, by varying the number of stator windings, it is possible to adapt both the performance curve and the efficiency curve to the load characteristics. In this way, it is possible, for example, to ensure that the idle frequency of rotation of the motor vehicle is covered by an optimum efficiency zone.

Regulatory Area 1:

In this control region I the field current Ie is set to its maximum possible value, that is, Ie = 1Emax. This maximizes the voltage of the magnet wheel in this lower region. Due to the low rotational frequency, the phase voltage Us is still so small as to the voltage of the vehicle electrical system that the voltage setting area _{UmX of the} pulse inverter PWR in the control region 1 is not exceeded. Therefore, the phase voltage Us is still less than the maximum voltage Umax adjustable by the PWR pulse inverter. Phase position and phase current can therefore be set to maximum output power without limitations. The maximum possible phase current is limited only by heating up the machine. With a constant phase current Is, the maximum output power of the machine also increases in proportion to the rotational speed in the control region.

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With the angle vj, as defined in Fig. 4, a longitudinal current Id and a transverse current I _lt arise for which l _d = I _with .sm _Ý = ₉ = Ι-Ι, .μ _ψ for the output power of a synchronous machine with high poles :

® · 4 «· Λ · 4 (i, - i) · 2? · * Π (2Ψ) t 2 co: electric angular frequency of stator currents

Mti _e : coupling inductance between rotor and stator

From the above equation Is = Is (Pgen, ψ), it is possible to determine the optimum angle M / _ _0Pt for the required generator Pgen power G at which the phase current assumes a minimum value.

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H / _{op (} = arctane

2 - ^ - C ^f Β ² AC 2-AC _ B · sin Ψ ^Smin ~ 2 - /. Cos (2T) * * · · • • • · »«

Minimizing the phase current by setting the optimum angle vj / ppt for the required generator Pgen power therefore results in minimum ohmic phase losses at the maximum possible excitation current Ιε ⁼ Ιειμ8χ. Since the electrical ohmic losses in the phase windings, despite the very low outputs, are still considerably greater than the electrical losses in the field circuit, the machine operates in the control range with maximum efficiency.

From a certain power-dependent rotational frequency indicated by the limit line N.12 in Fig. 3, the phase position of the phase currents can no longer be set by the PWR pulse inverter in accordance with the control region strategy I. In this case, the phase voltage the Umax voltage of the PWR pulse inverter given the actual Ubisi voltage between the circuits. This leads to a second control region 2 in which the phase voltage must be limited to its maximum value by suitable machine guidance.

Regulatory Area 2:

In the control region 2, 1E ⁼ 1Emax is further set. Now, however, the phase position of the phase current is selected so that the phase voltage impressed maximum value Us = U _max adjustable pulsed inverter PWR. The phase position of the phase current shall be selected so that the attenuation field of the air gap does not exceed the voltage setting range Umax of the PWR inverter.

Magnetic wheel and constant phase output power of generator G:

Using the angle δ of the voltage Us = U _max, p = --- U ^r Soll 2 ^U .sin (g) + ^ '

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At a given maximum constant phase voltage Umax, the required generator power G can be adjusted by changing the angle δ of the magnet wheel. For each required power, an angle δ = δ (Ρ _ίΟ ιι) can be set within the power range of the generator G.

If the angle δ of the magnet wheel is set to δ = δ (Ρ ₈₀ ιι) of the machine, the setting range of the PWR pulse inverter is not exceeded and the condition Us = U _max is maintained.

Adjustable longitudinal current and transverse current arise from the following relationships:

 ů ^ -sinÓ

Excitation current Ie longitudinal and transverse current Id _{and the} current I is uniquely defined by the state machines in dependence on the desired power Pgen. generator G.

In area 2, the machine will have a reactive power Pb. With decreasing output power (Part Load operation), coscp = 1 will finally be reached, ie the phase current and phase voltage are in phase. Boundary line N23. this limit. However, at even less power, it makes sense to operate the machine with cos <p = 1 to maximize efficiency. This is done by the regulatory area 3.

Regulatory Area 3:

The control area 3 is characterized by the operation of the generator G with a power factor cos <p = l, i.e. the phase current and the phase i

9 99 99 · 99 9 9 9

9,999,999

99 · 9 99 99 99 99 The voltages are in phase. The control region 3 corresponds to the operation of the generator G with passive diode rectification. This control region 3 is set from the middle range of the rotational frequencies when operating at a partial setting. For a given case of constant phase voltage Us = U _max, the maximum efficiency of the generator G is generated. To set this state, the excitation current is regulated to produce φ = 0, ie reactive power is Pb ⁼ 0 · by the line Nn, they cannot be formed by the control region 3, since in this case the drive current Ιε> Ιειπιχ is required.

The phase current value for the control region 1 arises from the relation

P j ^Oen

The desired angle δ of the magnetic wheel, the longitudinal current Id, the transverse current I _a and the excitation current Ie are calculated from the equations of the synchronous machine with excellent poles according to the relations a aL _and 'I _with Ί ^{= arctan} 7 ň ~ r Λ = Λ - ^sin .

<W | S ^ max //

I _q = I _s - cos (č) / _F = - ¹ - - ((U ^ -R, I _s ) · cqsS-a> -L _d I _s · sinO)

This fully defines the machine guidance for the control area 3.

The control structures described in control region 1-3 can cover all normal operating states of the machine.

9 99 • 999 ··

Regulatory Area 4:

The control region 4, which will be described below, serves firstly to ensure a high control dynamics with sudden unloading. Furthermore, this control function is an additional overvoltage protection function,

If the actual voltage value Ugist exceeds the adjustable overvoltage threshold, the normal operation of the pulse inverter is abandoned and the three-phase generator outputs are short-circuited with the pulse inverter switches. The overvoltage thus drops very quickly. At the same time, the field current of the machine is reduced, for example by rapid field weakening. If the output voltage reaches an adjustable undervoltage threshold that is below the setpoint output voltage Ubsoii, the machine will be guided again according to control region 1-3.

Execution of the method in terms of regulation:

In principle, it is possible to determine the limits between the individual control regions by numerical calculation and to determine the excitation current as well as the longitudinal current and the transverse current using the equations shown. However, this is very complicated in terms of numerical calculation. If the whole system is to be implemented in a motor vehicle, there is only limited performance of the computers available for cost reasons in that vehicle.

One possibility to avoid these difficulties lies, for example, in a table-oriented manner. The master controller has inputs Psoii, n _£ , Ub and outputs Ie, Id, L _a , Is and This dependency can be represented by a multidimensional table. This table contains the parent controller equations calculated off-line, not in separate mode (control area 1-4).

Claims (10)

PATENT CLAIMS A method of optimizing performance and efficiency of a generator having an associated bridge of a transducer, in particular a synchronous machine, wherein the excitation current flowing through the excitation winding is controlled such that the generator output voltage reaches a predetermined height and additionally regulates the generator phase currents. The method according to claim 1, characterized in that at least three control regions are formed in which the driving current and the phase currents of the generator are controlled according to various criteria. Method according to claim 1, characterized in that the formation of the rotation frequency control regions is carried out in dependence on the generator output power (Pgen) and / or the generator rotation speed (no). Method according to claim 1 or 2, characterized in that the control is carried out in such a way that, for each frequency of rotation of the generator and for each desired power of the generator, the field current and / or phase currents are arbitrarily selected. Method according to one of the preceding claims, characterized in that in the first control area the field current is set to its maximum possible value, in the second control area the field current is also set to its maximum value, but the phase position of the phase current is In the third control region, the generator is operated so that the phase current and phase voltage are in phase, and therefore the power factor is cos φ = 1 and the excitation current is regulated so that the angle φ is formed. = 0. «Fcfcfcfc fcfcfcfc fc ·· fcfc fcfcfc fcfc fc fc · fcfcfcfc fcfcfc · fcfcfc · ·« fcfc fc * fcfc Method according to one of the preceding claims, characterized in that in the fourth control region, after exceeding a predetermined threshold voltage of the generator windings, the corresponding control of the converter elements is short-circuited and the field current is reduced. Method according to one of the preceding claims, characterized in that the quantities required for regulation, ie the field current setpoint (Iesou), the phase current longitudinal component (Idsoii) and the transverse phase current component (I _qS oti) are determined using multidimensional tables . 7. A device for control, optimized in terms of power and efficiency, of a generator with associated bridge of a converter, in particular a synchronous machine, with a controller for controlling the excitation current flowing through the excitation winding and another controller for regulating the phase currents of the generator, Both these controllers are connected by a superior controller, which supplies them with the required values. Device according to claim 8, characterized in that the fourth regulator acts as a voltage regulator and compares the voltage delivered by the converter to the desired voltage and supplies the desired regulator with the desired power. Device according to claim 7 or 8, characterized in that the converter bridge is designed as a pulse inverter with a predetermined number of elements and with an intermediate circuit capacitor. Device according to one of the preceding claims, characterized in that the device is part of a motor vehicle and comprises at least one computing means for performing the computing means 9. 9 9 9 9 • 9 9 · ·· 44 procedures and / or to communicate with a computer in the vehicle.